Blop's help system is HTML-based, and it is the same as what you can find at its home-page http://blopplot.sourceforge.net/. You can look up a desired keyword in the documentation by typing help("keyword"); at your blop> prompt (interactive session), or typing blop -h keyword at your shell prompt. This will do the following things:

• If keyword ends in .h or .cc, this is treated as a source file, and if the file exists, it is displayed. By this way you have quick and direct access to source files, if you are a bit familiar with them.
• Look up your keyword in a help index file, which is located at INSTDIR/doc/help-index (INSTDIR is by default /usr/local/blop, unless you changed it when installing blop). (Additionally, if $HOME/.blop-help-index exists, it looks up your keyword also in this file, so you can specify your own lookup method for your favourite topics). These files specify, which docfiles are the best for certain keywords (the format of these files is line-based: words before the colon are the keywords, words after the colon are the filenames relative to INSTDIR/doc).
  • If one file is dedicated for this keyword, that file is shown in your browser
  • If several files are dedicated for this keyword, a list of choice is shown.
  • If no files are dedicated, all docfiles are scanned for this keyword, and the results of this search are offered to you

If you provide an initial '?' character, the search will be forced (the following keyword will be searched in the whole documentation). For example: help("?canvas");

If the help index file did not contain your keyword, and your keyword was not found in any of the other docfiles, a messages stating this will appear in your terminal (where you issued the command).

In order to browse this file you will need a HTML-browser. Blop is intelligent enough to look for quite some known HTML browsers installed on your machine (kfmclient (load into default kde browser), firefox, mozilla, gnome-help-browser, lynx, less, cat), in this order. When a helpfile is to be displayed, these commands are tried in sequence, until one of them succeeds. Blop tries to figure out if you are using a graphical terminal from the existence of the environmental variable DISPLAY. If this variable is not set, the graphical browsers will not be made available, only 'lynx' and 'less'. To specify your preferred HTML-browser as the help viewer for blop, you have can do this:

• Set the environment variable BLOP_HELPVIEWER before invoking blop. (In bash say
  export BLOP_HELPVIEWER="my_browser %f";
  In tcsh say
  setenv BLOP_HELPVIEWER "my_browser %f";).
  The '%f' in this variable will be replaced by the filename to be displayed.

There are some specific 'topic's:

documentation

The index of the documentation is displayed

tutorial

You are directed to the tutorial immediately

keywords

A list of available keywords (for which a dedicated topic exists) is printed to the standard output

You often find yourself not running blop interactively, but instead, writing a script. Thus, you do not have any running blop process, but you would like to look for help. It is painful to start a blop process, type help("something"); and then terminate the process, etc. Therefore the command line option -h is reserved to make your life easier: saying
blop -h topic
will do this job for your.